The present invention relates generally to reducing the cost of detecting a condition of close proximity of a large object, such as a human face, relative to the location of a display screen, such as a capacitive touch screen, of a mobile communication device such as a smart phone. More particularly, the present invention relates to circuitry and methods for detecting when a relatively large, somewhat conductive object, such as a human face, is in sufficiently close proximity to a touch screen display (or other display) of a cell phone, smart phone or the like to de-activate the touch screen and thereby reduce power consumption during phone conversations when touch screen functions are not needed.
Presently available cell phones, smart phones, and the like need to be able to detect when a face or other large, relatively flat object is sufficiently close or “proximate” to a touch screen (or other display) of the cell phone, smart phone, or the like in order to save power and/or prevent accidental input to a smart phone or the like due to accidental touching of the touch screen by disabling features of the touch screen. Various known touch screen architectures that are suitable for use in state-of-the-art smart phones are well known. The conventional capacitive touch screen of a smart phone typically utilizes an infrared (IR) sensor including a small IR emitter-detector diode pair to detect reflection of an emitted IR beam from the surface of a relatively large object such as a human face, as shown in Prior Art FIG. 1.
Referring to FIG. 1, a conventional state-of-the-art smart phone 1 includes a touch screen 13A which is controlled by a touch screen controller circuit and associated software. Smart phone 1 has a “proximity” detection system including an emitter-detector pair of IR diodes collectively designated by reference numerals 4A and 4B. The transmitter or emitter diode 4A emits an IR beam 6A which may be of steady intensity, but preferably is of periodic intensity to reduce power consumption. In FIG. 1, smart phone 1 is shown as being held close to, i.e., proximate to, the cheek 5 and/or ear 5A of a person having a private phone conversation. The transmitter diode 4A emits IR beam 6A, which is reflected as IR beam 6B from the ear and/or face of the person. Reflected beam 6B is detected by the detector diode of the emitter-detector IR diode pair 4A,B. If no human face or other suitably large object is proximate to IR emitter-detector pair 4A,B, then IR beam 6A either does not exist or is too weak to be detected.
If reflected beam 6B is detected, that causes associated detection circuitry in smart phone 1 to deactivate part or all of the functionality and associated circuitry of touch screen 13A as long as touch screen 13A is receiving reflected beam 6B, that is, as long as the cheek or ear of the person remains sufficiently close or proximate to emitter-detector IR diode pair 4A,B.
If the surface of touch screen 13A in FIG. 1 is in sufficiently close proximity to the user's face 5 that a speaker or sound transducer in smart phone 1 is close to (i.e., is within about an inch of) the user's face 5 or ear 5A so that the user can speak directly into the microphone of smart phone 1, then reflected IR beam 6B is detected. In this case, touch-sensing functionality is not needed so touch screen 13A is disabled or deactivated. This prevents any inadvertent touching of the touch screen from causing an unintended or accidental input to smart phone 1 while it is being held up to the cheek 5 or ear 5A. The disabling of touch screen 13A also significantly reduces the power consumption of the smart phone.
Unfortunately, the cost of using such IR sensors and associated circuitry for proximity detection of a smart phone or the like is often unacceptably high. It would be highly desirable to be able to avoid the high cost of the IR sensors and associated circuitry and nevertheless reliably achieve proximity detection of a user's face to the touch screen surface while it is being held close to the user's face.
Thus, there is an unmet need for a less costly way of determining whether a large object, such as a human face, is presently located in sufficiently close proximity to a conventional touch screen of a mobile communication device to allow some of the circuitry associated with the touch screen display to be disabled while it is being held close to the user's face and to also avoid the high cost of IR sensors and associated circuitry conventionally used for such proximity detection.
There also is an unmet need for a less costly, less power-consuming way of determining whether a large object, such as a human face, is presently located in sufficiently close proximity to a conventional touch screen of a mobile communication device to allow a portion of the circuitry associated with the touch screen to be disabled while it is being held close to the user's face and to also avoid the high cost of IR sensors and associated circuitry conventionally used for such proximity detection.
There also is an unmet need for a lower-cost, less power-consuming way to achieve detection of the proximity a user's face relative to the touch screen surface of a smart phone while it is being held close to the user's face and to also avoid the high cost of IR sensors and associated circuitry conventionally used for such proximity detection.
There also is an unmet need for a lower-cost, less power-consuming way to avoid inadvertent input signals to the smart phone from being generated by accidental touching of the touch screen surface of the smart phone while it is being held close to the user's face and to also avoid the high cost of IR sensors and associated circuitry conventionally used for such proximity detection.